Protein composition and foam abatement



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Patented Nov. 5, 1940 K 22203160, PROTEIN coMrosr'rIoN,ANnj o B Francis Clarke Atwood, Newton, Mas s., assignorl to Atlantic Research Associates, Inc., Wilming- 1 t,

ton, Del., a corporation of Delaware Application January 25, 1933, Serial No. 186,909

7 Claims. c1. 134 12) No Drawing.

This invention relates to novel protein compositions having various desirable characteristics, including minimum foaming characteristics and to methods of abating or preventing foaming in aqueous protein compositions.

The invention has for one of its objects the abatement or prevention of foaming in protein compositions such as aqueous compositions 'embodying casein produced from animal milk, or from the proteins of soya bean, or other seeds;

and the foaming in compositions embodying blood and egg albumen; and in compositions of other proteins produced from leguminous materials more frequently called vegetable caseins.

The invention has for another object the production of novel and highly useful protein compositions, and particularly casein compositions characterized by their stability over long periods of time, by increased plasticity and having other characteristics which render them especially suitable for the manufacture of'paints, emulsions, glues, sizes, coating compositions, transparent films, and as the basis for printing inks.

With these objects in view and such others as may hereinafter appear, the invention consists in the novel protein compositions and in the method of abating and preventing foaming in aqueous protein solutions and. dispersions hereinafter described and particularly defined in the claims at the end of this specification.

In general, the present invention contemplates the abatement or prevention of foam in aqueous protein compositions of the character above set forth by the introduction into the composition of an anti-foaming agent consisting of one or more alcohols of the type substantially immiscible with water, i. e., having low solubility therein, and in :a sufficient amount with respect to the water ,content of the composition such that there is present an amount of undissolved alcohol in excess of that required to satisfy the solubility thereof in the water content of the composition. The alcohols which I have found most suitable "are preferably of the type having boiling points higher than water and the effectiveness of the 'fo'regoing materials as anti-foaming agents in I order to'prevent or abate foam has been found ,br foam abatement and prevention in aqueous to its former level in solutions of proteins of the character" above specified, I have found-those alcohols which are substantially immiscible with water to be" most efficient for such purposes and-I have further discovered that in addition to such alcohols, those alcohols which are partially soluble in water may be successfully used asfoamabating or foam eliminating reagents'provided that a sufficient amount of the alcohol be incorporated so as to exceed the amount required to satisfy the 'solu? bility of the alcohol-in the aqueous solutions of the proteins so that there is presentat least a molecular layer of undissolved alcohol between the surface of the protein solution and the'surface of the adjacent air layer.

My theory concerning the'for-mation and the abatementzor prevention of foam in these aqueous solutions of proteins concerns -th'e-re-- action probably taking place attheinterface between the protein solutiomthe air phase and the film or layer of anti-foam material. form the foam in the first place, it is probable that the concentration of the protein material becomes greater in the interfacein that the surface tension ofthe water is thereby lowered thus enabling the bubble of f am to form. Whenan anti-foam material is pr sent inan amount exceeding the amount required to; saturate the protein film with the anti-foam material, then the concentration at-the interface between the antifoam material and the protein solution-becomes such that the protein solutionis actually precipitated out of its water solution or else it is so low in concentration that it cannot any longer lower the surface tension of the water. The surface tension of the water, therefore, becomes normal or possibly greater than that of ordinary water due to the introduction of the anti-foam material. As a 'consequence,'the surface tension now becomes so great that the'bubble bursts and Of foam In order to the protein solution of the bubble sinks back the main body of, the solution. I j f In support of my theory of foam prevention and foam abatement in protein solutions'of fthe character specified, my experiments 'have' in- I dicated that it is possible-to add'sufficient of=the foam abating or preventing material :tosaturate the protein solution in which-*itis -desiredto destroy the foam, and 'while'the' team ma s'ubside during the addition of the anti-foaming agent, yet-the foam'can be brought backassoon as: the agent is completely'mixed or dissolved in the protein or foaming solution.v On'theother hand, if the amount ,of-anti-foaming material is 0 points higher than that of water.

sufficient to not only saturate the foaming solution but yield a separate phase as well, then the desirable efiect of the anti-foaming agent in destroying the foam is rendered permanent.

In order to accomplish this result, I have found that compounds substantially immiscible in water, 1. e., of at least limited solubility therein, are necessary and that the polar relation with respect to the water must be such that some part of the molecule should exhibit solubility in water thereby so polarizing itself with respect to water that there is not a chaotic solution of the molecules next to the molecular layers but rather that part of the molecule which is normally soluble or slightly soluble in water will form a hydrophilic layer next to the protein solution and thereafter accomplish the desired result of breaking down the foam. A large number of experiments have indicated that the present anti-foam alcohols including those substantially immiscible in water, i. e., those of limited solubility in water, when incorporated into an aqueous solution of a protein of the character described and in an amount greater than that necessary at any particular time to satisfy the solubility of the particular alcohol in the water, results in the presence of at least a molecular layer of undissolved alcohol between the surface of the protein solution and the adjacent surface of the air layer, producing the desired effect in abating or eliminating foam from this character of solutions. Among the alcohols with which I have experienced satisfactory results may be mentioned butyl alcohol, amyl alcohol, hexyl alcohol, capryl alcohol, decyl alcohol, cetyl alcohol, lauryl alcohol, fenchyl alcohol, benzyl alcohol, cinnamyl alcohol, alpha terpineol furfural alcohol, and others which are principally included in the classes of alkyl or aliphatic, aryl, aromatic or heterocyclic alcohols having boiling Included in the above described general class are liquid lower aliphatic alcohols, examples of which are butyl alcohol, amyl alcohol and hexyl alcohol.

The present protein composition embodying, as

has been stated, suflicient alcohol selected from the classes of the alcohols described, and having boiling points higher than the water, finds particular use as a coating material and the prevention of the formation of foam during the application of the composition to a surface and particularly to a porous surface, such as paper or a plastered wall. As the composition sinks into the wall or paper a certain amount of air is displaced which is forced out through the layer of the coating material as the latter is drying down. If the surface tension of this film as it is drying is so low that the air being forced out can readily form a bubble, then as this bubble dries it leaves a crater or a pimple in the finished film. This not only tends to weaken the film, but leaves unsightly marks or effects upon the surface. If on the other hand the composition embodies any of the present foaming agents in a suificient amount so that there is always present an undissolved layer of the anti-foaming material, the surface tension of the film of coating composition is not low enough to form bubbles, and in addition the relatively high surface tension thereof tends to prevent the air from coming out through the film, and when it does come out the air is immediately released and the surface of the film pulled together again by the high surface tension. By utilizing such an anti-foaming alcohol the formation of a hard skin and surface imperfections is prevented over longer periods of time after the application of the film.

As above stated the present invention is applicable to stable casein solutions including animal and vegetable caseins as milk and soya casein, stable solutions of resinified casein, i. e. the reaction products with casein of various fatty acids, organic acids, polyoses and soluble polyatomic alcohols, and also solutions of ordinary resinified casein and particularly to those protein compositions containing pigments such as paint and ink and paper coating compositions. The present anti-foam materials are particularly effective in those protein solutions which show the greatest tendency to foam, for example, in casein solutions where the concentration of casein is less than one part to eight parts of water.

As illustrative of typical compositions embodying the present invention, the following examples Suspend casein in water and heat with resinifying agent until clear solution is obtained.

Casein, when dispersed in water forms a gellike structure at some temperatures. In general the casein type of proteins form a gel without a short melting point. It is the general nature of such a gel to shrink over a long period of time in such a way that there may be formed a liquid and a fibrous or sponge like structure of higher melting point or which may even be insoluble. The process by which this gel contracts and expresses the liquid is called syneresis. I have found in other inventions that the syneresisof my casein solution or even a hydrolitic cleavage of the casein molecule may be indefinitely deferred by heating the casein solution to a temperature of to degrees F. for an hour or more; by use of plumping or swelling salts such as sodium and ammonium fluoride, sodium formate, sodium 2,220,700 by th elimination of the air which otherwise tends to impart to the solution an elasticity or yield value which is false and disappears as soon as the air is eliminated. Under the microscope nearly all casein shows minute air bubbles and these air bubbles areretained in the casein as it swells and goes into solution. It is extremely difllcult to remove this air because of the finely divided condition of the bubbles and the present anti-foam agents assist in eliminating the occluded air as well as the .air which is entrapped during the mixing process, so that. the resulting change in viscosity makes for better flow properties and better adhesive characteristics. In other words, the elimination of the air by this method and the consequent increased wetting effect makes for better cohesiveness within my casein solution and as a consequence it becomes very much simpler as a practical matter for the user of paint or other casein products to thin the composition with water or similar thinners. In some cases where the alcohol has definite hydrophilic properties I have found that the casein solution above described to be substantially less viscous than comparable solutions thinned with an equivalent amount of water, and much less viscous than before the addition of the solvent or solvents. The casein solutions thinned with the alcohols as above described, will flow easily, remain smooth in appearance, retain their useful adhesive properties, and remain stable for long periods of time regardless of whether the solution has been made slightly basic (alkaline) or slightly acidic. The

acidic solutions will, of course, have a pH of less than 7.0.

This application is .a continuation in part of my copending application, Serial No. 442,997, filed April 9, 1930.

Having thus described the invention, what is claimed is:

1. A process for preventing the foaming of aqueous casein containing compositions which comprises incorporating with said composition normal butyl alcohol.

I 2. A casein paint containing normal butyl alcohol.

3. A casein paint containing a partly water soluble aliphatic alcohol.

4. A casein paint containing amyl alcohol.

, 5. A casein coating composition containing a 25 partly water-soluble aliphatic alcohol.

6. A casein coating composition containing amyl alcohol..

7. A casein coating composition containing normal butyl alcohol.

FRANCIS CLARKE ATWOOD. 

